Lice Symptoms and Signs

Lice infestation on the human body (also known as pediculosis) is very common. Cases number in the hundreds of millions worldwide. While lice can occasionally cause significant illness (typhus, relapsing fever, and trench fever), a lice infestation is generally more of an itchy and embarrassing experience than a serious medical problem. Three distinct presentations of lice infection exist and each is caused by a unique parasite.

Head lice (Pediculus humanus capitis) is by far and away the most common infestation and favors no particular socioeconomic group. A genetically close "cousin," Pediculus humanus corporis, is responsible for body lice and is more commonly associated with poverty, overcrowding, and poor hygiene. Pubic lice ("crabs") is caused by Pthirus pubis and is transmitted by intimate and/or sexual contact.

Lice infestation is a uniquely human experience. Lice do not jump or fly from host to host. They cannot be transmitted via animals but may be transferred by person to person via direct contact and by fomites (inanimate objects -- for example, caps, combs, sheets, etc).